Simplify the following expression: $p = \dfrac{-n + 4}{5n + 10} \div \dfrac{1}{9}$
Answer: Dividing by a number is the same as multiplying by its inverse. $p = \dfrac{-n + 4}{5n + 10} \times \dfrac{9}{1}$ When multiplying fractions, we multiply the numerators and the denominators. $p = \dfrac{(-n + 4) \times 9} {(5n + 10) \times 1}$ $p = \dfrac{-9n + 36}{5n + 10}$